When Dean Potter and Graham Hunt died BASE jumping in Yosemite, on May 16, they ignited a long-smoldering debate about the federal ban on jumping in U.S. national parks. Within days a petition on Change.org began circulating to pressure the National Park Service to end the ban.

For jumpers, the argument is twofold. The ban is arbitrary and outlaws a behavior that poses no threat to anyone but the jumper. More important, making it legal could make it safer. “If you decriminalize it,” says Rick Harrison, director of the United States BASE Association, “people can jump in full daylight, from the best exit points, using their best gear.”

BASE advocates argue that the ban encourages the use of older gear — cheaper to replace if rangers confiscate it — and leaping from cliffs at dusk, when rangers can’t see them. That’s also when winds are unpredictable and shadows wreak havoc on a jumper’s depth perception. “That’s why I quit doing illegal jumps,” says professional BASE jumper Jeb Corliss. “Because you end up jumping in darker conditions or a bad wind.”

Park officials say safety isn’t the issue. “We get 4 million visitors a year,” says Yosemite spokesman Scott Gediman. “People come here to hike, fish, and enjoy the natural beauty, so we look at the impact of every activity on every other activity.” Mountain biking, for example, is prohibited to protect hikers and trails; concerts are outlawed because of the noise.

In 1980 the park attempted a brief trial run at legalization: Crowds gathered, jumpers rode bicycles and skateboards off El Capitan, and, says Harrison, one group of skydivers even drove a flatbed truck up a wilderness hiking trail. “There was a circus-like atmosphere,” he says. Skepticism deepened in 1999 when a skydiver named Jan Davis made a protest jump off El Capitan, in full view of rangers, to prove the sport’s safety. She failed to open her parachute and hit at terminal velocity. “I’ll never forget that,” says Gediman.

“The ground shook. Car alarms went off. A ranger who worked with me freaked out.”

BASE jumping is legal in much of Europe. The Swiss town of Lauterbrunnen, for example, sees 15,000 to 20,000 jumps annually. But there are still risks.

An average of six BASE jumpers die each year in Switzerland, and farmers have complained about deaths in their fields. But the Swiss BASE Association now mitigates this with a jumper’s code of ethics and “landing cards” authorizing landing only in designated areas. Swiss authorities also require jumpers to carry liability and rescue insurance. Harrison argues that a similar system could work in the U.S.: Jumpers could be required to prove sufficient experience, and remote cliffs like Half Dome could be opened to the sport while highly visible ones like El Capitan remain illegal. But pushing the limits is central to BASE-jumping culture, and even with those measures, there still could be fatalities as jumpers test their bounds.

“In theory, it should be safer from big cliffs like El Cap,” says Chris McNamara, a leading U.S. wingsuiter, “because you can fly farther away from the face before you open your parachute, but then you have people like me thinking, ‘Why fly safely when I can buzz all this terrain and have the most incredible sensation known to humans?’ ”

For now, though, all these arguments are purely theoretical. “It’s illegal,” Gediman says. “And we have no intention of changing that.”